Downhole fluid control is necessitated at various stages of oilfield production. Limiting or preventing loss of fluids provided downhole is desirable in order to increase efficiencies or prevent damage to the formation or environment. One manner of preventing fluid loss, also referred to as leak-off, involves the use of filter cakes which form a film like barrier. Various solids, gels, sealants, foams or other additives, such as fluid loss control agents, can be pumped downhole to form a filter cake on the formation face. The filter cake blocks pores and provides an impermeable layer to fluid thereby diverting fluid and preventing fluid loss. However, due to this blocking action, the filter cake can inhibit subsequent desirable hydrocarbon production. Accordingly the filter cake may thereafter be removed by providing further additives such as breakers or acids which can dissolve or disrupt the formed filter cake. Self-degrading filter cake material has also been employed, which subsequent to forming the filter cake downhole, over time degrades and returns to the surface.
Fluid loss control agents can be used during well stimulation processes. For example, during hydraulic fracturing, a filter cake forming material can be employed to prevent leak off and direct the flow of fracturing fluid to locations in the formation to cause primary fractures and/or microfractures and wormholes. The filter cake can then be removed or self-degraded for subsequent hydrocarbon production.
Such fluid control agents can be employed at various other phases of well production. For example, some formations in addition to hydrocarbon producing zones may also have water producing zones. Fluid control techniques and agents can be employed to limit the flow of water and improve the flow of hydrocarbons. Such operations can be referred to as conformance operations for example.
Such fluid control is desirable in a large number of operations and treatments including drilling, drill-in, completion, stimulation, sand control (for example gravel packing, frac-packing, and sand consolidation), diversion, scale control, water control, and others.
It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.